JP3678227B2 - Photocatalytic coating composition for metal substrate, photocatalytic metal material obtained using the same, and method for producing photocatalytic metal material - Google Patents
Photocatalytic coating composition for metal substrate, photocatalytic metal material obtained using the same, and method for producing photocatalytic metal material Download PDFInfo
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- JP3678227B2 JP3678227B2 JP2002270046A JP2002270046A JP3678227B2 JP 3678227 B2 JP3678227 B2 JP 3678227B2 JP 2002270046 A JP2002270046 A JP 2002270046A JP 2002270046 A JP2002270046 A JP 2002270046A JP 3678227 B2 JP3678227 B2 JP 3678227B2
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- photocatalytic
- coating composition
- photocatalyst
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- film
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- 230000001699 photocatalysis Effects 0.000 title claims description 63
- 239000008199 coating composition Substances 0.000 title claims description 56
- 239000000758 substrate Substances 0.000 title claims description 44
- 229910052751 metal Inorganic materials 0.000 title claims description 40
- 239000002184 metal Substances 0.000 title claims description 40
- 239000007769 metal material Substances 0.000 title claims description 20
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- 238000000576 coating method Methods 0.000 claims description 104
- 239000011248 coating agent Substances 0.000 claims description 103
- 239000011941 photocatalyst Substances 0.000 claims description 89
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 150000001875 compounds Chemical class 0.000 claims description 24
- 229920000620 organic polymer Polymers 0.000 claims description 23
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 17
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical group O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 239000000843 powder Substances 0.000 claims description 16
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 15
- 239000003795 chemical substances by application Substances 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 11
- 239000000126 substance Substances 0.000 claims description 11
- 239000007787 solid Substances 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- 239000002202 Polyethylene glycol Substances 0.000 claims description 8
- 239000003125 aqueous solvent Substances 0.000 claims description 8
- 229920001223 polyethylene glycol Polymers 0.000 claims description 8
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical group O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 8
- 150000002736 metal compounds Chemical class 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 4
- 239000001506 calcium phosphate Substances 0.000 claims description 4
- 229910000389 calcium phosphate Inorganic materials 0.000 claims description 4
- 235000011010 calcium phosphates Nutrition 0.000 claims description 4
- 239000003960 organic solvent Substances 0.000 claims description 4
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims description 4
- 229920001451 polypropylene glycol Polymers 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 239000008239 natural water Substances 0.000 claims description 2
- 239000012046 mixed solvent Substances 0.000 claims 1
- 239000010408 film Substances 0.000 description 121
- 229910052782 aluminium Inorganic materials 0.000 description 46
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 46
- 239000000463 material Substances 0.000 description 45
- 238000012360 testing method Methods 0.000 description 43
- 230000000052 comparative effect Effects 0.000 description 15
- 239000002245 particle Substances 0.000 description 12
- 239000003973 paint Substances 0.000 description 11
- 239000011230 binding agent Substances 0.000 description 10
- 238000001035 drying Methods 0.000 description 10
- 239000002585 base Substances 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 8
- 238000005755 formation reaction Methods 0.000 description 7
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000011347 resin Substances 0.000 description 6
- 229920005989 resin Polymers 0.000 description 6
- 239000010407 anodic oxide Substances 0.000 description 5
- 239000012298 atmosphere Substances 0.000 description 5
- 239000004566 building material Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- -1 polysiloxane Polymers 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 229910052910 alkali metal silicate Inorganic materials 0.000 description 3
- 150000004703 alkoxides Chemical class 0.000 description 3
- 230000000844 anti-bacterial effect Effects 0.000 description 3
- 238000004040 coloring Methods 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 150000002334 glycols Chemical class 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 description 2
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 description 2
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 2
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 description 2
- 239000005642 Oleic acid Substances 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000003618 dip coating Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 125000000524 functional group Chemical group 0.000 description 2
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 239000011135 tin Substances 0.000 description 2
- 238000009281 ultraviolet germicidal irradiation Methods 0.000 description 2
- 230000002087 whitening effect Effects 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- QTWJRLJHJPIABL-UHFFFAOYSA-N 2-methylphenol;3-methylphenol;4-methylphenol Chemical compound CC1=CC=C(O)C=C1.CC1=CC=CC(O)=C1.CC1=CC=CC=C1O QTWJRLJHJPIABL-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 229920002845 Poly(methacrylic acid) Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- MQRWBMAEBQOWAF-UHFFFAOYSA-N acetic acid;nickel Chemical compound [Ni].CC(O)=O.CC(O)=O MQRWBMAEBQOWAF-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000007743 anodising Methods 0.000 description 1
- 229910052586 apatite Inorganic materials 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 229910001593 boehmite Inorganic materials 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
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- 239000008119 colloidal silica Substances 0.000 description 1
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- 125000001033 ether group Chemical group 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
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- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000007602 hot air drying Methods 0.000 description 1
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052809 inorganic oxide Inorganic materials 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
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- 229910001463 metal phosphate Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229940078494 nickel acetate Drugs 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000172 poly(styrenesulfonic acid) Polymers 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
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- 229940005642 polystyrene sulfonic acid Drugs 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
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- 125000005372 silanol group Chemical group 0.000 description 1
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- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
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- VEALVRVVWBQVSL-UHFFFAOYSA-N strontium titanate Chemical compound [Sr+2].[O-][Ti]([O-])=O VEALVRVVWBQVSL-UHFFFAOYSA-N 0.000 description 1
- 125000001174 sulfone group Chemical group 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
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- 229910052726 zirconium Inorganic materials 0.000 description 1
Description
【０００１】
【発明の属する技術分野】
この発明は、金属基材、特に限定するものではないが、アルミニウム又はアルミニウム合金からなるアルミニウム材の表面に塗布して光触媒塗膜を形成するための金属基材用の光触媒塗料組成物、及びこれを用いて得られた光触媒性金属材料、並びにこの光触媒性金属材料の製造方法に関する。
【０００２】
【従来の技術】
【特許文献１】
特開2000-254,518号公報
【特許文献２】
特開2001-10,877号公報
【特許文献３】
特開2001-98,187号公報
【特許文献４】
特許第3,210,544号公報
【特許文献５】
特許第3,210,546号公報
【特許文献６】
特開平10-174,883号公報
【０００３】
酸化チタンに代表される光触媒活性を有する金属化合物（以下、単に「光触媒」ということがある）は、光エネルギーを利用して種々の有害物質を分解でき、また、種々の製品の基材表面に塗布した場合、その基材表面を親水性化して表面に付着した汚れを容易に除去可能にすることから、多くの用途において注目されている。
【０００４】
そして、製品の基材表面において、このような光触媒活性を効率良く発現させるためには、先ず光触媒を製品の基材表面に確実に固定する技術が重要であり、一般には、光触媒の微粒子に光触媒固定用及び塗膜形成用を兼ねたバインダー樹脂を配合して塗料組成物を調製し、この塗料組成物を基材表面に塗布してこの基材表面に光触媒の微粒子が分散した塗膜を形成せしめ、これによって製品の基材表面に光触媒機能を付与する方法が行われている。
【０００５】
しかしながら、光触媒の持つ光触媒活性は、光照射によりその表面で酸化還元反応や活性酸素等の生成が起こることに起因しているため、有機樹脂系のバインダー樹脂を用いて塗料組成物を調製し、この塗料組成物を塗布して基材表面に光触媒塗膜を形成すると、この光触媒塗膜を形成しているバインダー樹脂が酸化され、あるいは、活性酸素の酸化作用により分解され、バインダー樹脂が消失して光触媒塗膜はその形態を維持できなくなり、光触媒の脱落が進行するいわゆるチョーキング現象が発現する。
【０００６】
そこで、従来においても、この光触媒塗膜のチョーキング現象に対する対策として、金属アルコキシドやポリシロキサンから得られる無機系バインダーを利用する方法が検討されている。しかしながら、この無機系バインダーを利用する方法は、塗膜形成反応速度が遅く、また、成膜時の体積減少が大きいために形成された光触媒塗膜にクラックが発生し易く、更に、塗膜硬化時に雨水と接触すると塗膜が白化し易い等の問題がある。
【０００７】
また、金属アルコキシドを使用するゾルゲル法で光触媒塗膜を形成する方法も提案されているが、この方法の場合には少なくとも３００℃以上の高温で処理する必要があり、例えばアルミニウム又はアルミニウム合金からなるアルミニウム材を用いた場合には、このような高温で熱処理を行うと、アルミニウム材自体の強度低下を引き起こす等、金属基材の種類によっては適用できない場合がある。
【０００８】
更に、光触媒塗膜のチョーキング現象に対する対策として、光触媒の粒子表面の一部を光不活性無機物質で部分的に被覆し、光触媒が直接にバインダーと接触しないようにし、これによってバインダーの劣化を防止する試みが行われており、そのための種々の方法が提案されている。
【０００９】
例えば、特開2000-254,518号公報には、チタンと珪素及び／又はジルコニウムとの複合酸化物におけるチタン含有率及び一次粒子径の最適条件を検討し、塗料への適用を試みている。
しかしながら、有機樹脂系のバインダーを使用した実施例と参考例によれば、光触媒活性をほとんど示さない顔料用酸化チタンにおいては酸化チタンの脱落がほとんど無いのに対し、光触媒活性を示す酸化チタンを用いた実施例では酸化チタンの脱離が認められており、有機系バインダーの劣化を充分に抑制するには至っていない。
【００１０】
また、特開2001-10,877号公報には、シリカにより表面処理された光触媒微粒子とコロイダルシリカとを含み、常温で容易に、かつ、薄膜状に塗工でき、しかも、透明性の高い光触媒コーティング組成物が記載されている。
しかしながら、この光触媒コーティング組成物は、コンクリート、モルタル等のセメント系下地材をその対象としており、金属材料への適用については全く検討されていない。
【００１１】
更に、特開2001-98,187号公報には、硬化して被膜を形成するアルカリ金属珪酸塩からなる塗膜形成要素と無機酸化物粒子及び／又はその前駆体で表面処理された光触媒性酸化チタン粒子とを含み、ｐＨが５〜９である光触媒性親水性コーティング組成物が開示されている。
しかしながら、この光触媒性親水性コーティング組成物も、ガラス、レンズ、鏡等の透明性が求められる基材の表面に塗装することを目的としており、金属材料への適用については全く検討されていない。
【００１２】
更に、特許第3,210,544号公報には、アルミニウム材からなる基材表面に陽極酸化皮膜を形成し、この陽極酸化皮膜上にスパッタ法、溶射法、レーザーアブレーション法、ゾル−ゲル法、メッキ法等の方法で光触媒活性を有する膜厚１μm以下の薄膜をコーティングした抗菌・抗黴性のアルミニウム建築材が開示されている。
しかしながら、このアルミニウム建築材においては、光触媒塗膜を形成する際にそれ専用の装置や焼成処理等が必要であることから、現場施工が困難であるほか、その補修作業も困難である。
【００１３】
更にまた、特許第3,210,546号公報には、アルミニウム材からなる基材表面に陽極酸化皮膜を形成し、この陽極酸化皮膜上に光触媒を含有する塗料組成物を電着塗装又は静電塗装によって塗装してなる抗菌・抗黴製の建築材料が開示されている。
しかしながら、この建築材料においても、光触媒塗膜を形成する際にそれ専用の装置や焼成処理等が必要であることから、現場施工が困難であるほか、その補修作業も困難であり、また、有機系の塗料成分を用いた場合には光触媒活性による劣化は免れない。
【００１４】
更にまた、特開平10-174,883号公報には、アルミニウム材からなる基材表面に陽極酸化皮膜又はベーマイト皮膜等の多孔質皮膜を形成し、この多孔質皮膜に浸漬等の手段で光触媒活性を有する酸化チタンゾルを化学吸着させ、水洗後に加熱乾燥して光触媒機能を有するアルミニウム材を製造することが記載されている。この方法においても、多孔質皮膜を有する基材を酸化チタンゾル液に浸漬するための処理槽が必要であるほか、加熱乾燥のための加熱装置も必要になり、現場施工が困難であるほか、その補修作業も困難である。
【００１５】
【発明が解決しようとする課題】
そこで、本発明者は、アルミニウム材等の金属基材の表面に塗布して容易にチョーキング現象のない光触媒塗膜を形成することができる光触媒塗料組成物について鋭意検討した結果、表面を光不活性無機物質で部分的に被覆して得られた部分被覆光触媒粉末、無機質造膜剤及び水溶性有機高分子化合物を含む光触媒塗料組成物を用い、これを塗布して得られた塗布被膜から水溶性有機高分子化合物を除去する後処理を行うことにより、容易に目的を達成できることを見出し、本発明を完成した。
【００１６】
従って、本発明の目的は、アルミニウム材等の金属基材の表面に塗布して容易にチョーキング現象のない光触媒塗膜を形成することができる光触媒塗料組成物を提供することにある。
また、本発明の他の目的は、アルミニウム材等の金属基材の表面にチョーキング現象のない光触媒塗膜を有する光触媒性金属材料を提供することにある。
更に、本発明の他の目的は、アルミニウム材等の金属基材の表面にチョーキング現象のない光触媒塗膜を備えた光触媒性金属材料を製造するための光触媒性金属材料の製造方法を提供することにある。
【００１７】
すなわち、本発明は、金属基材の表面に塗布されてこの金属基材の表面に光触媒塗膜を形成する光触媒塗料組成物であり、水系溶剤中の全固形分に対して、光触媒活性を有する金属化合物の表面を光不活性無機物質で部分的に被覆して得られた部分被覆光触媒粉末を１〜５０質量％の割合で、無機質造膜剤を３０〜８９質量％の割合で、及び、ポリエチレングリコール又はポリプロピレングリコールから選ばれた１種以上からなり金属基材に対して濡れ性を付与する重量平均分子量１０００〜１０００００の水溶性有機高分子化合物を１０〜５０質量％の割合でそれぞれ含有する、金属基材用の光触媒塗料組成物である。
【００１８】
また、本発明は、上記の光触媒塗料組成物を金属基材の表面に塗布し、次いで乾燥させた後、形成された塗布被膜中の水溶性有機高分子化合物を実質的に除去して得られた光触媒性金属材料である。
【００１９】
更に、本発明は、上記の光触媒塗料組成物を金属基材の表面に塗布し、次いで乾燥させた後、形成された塗布被膜中の水溶性有機高分子化合物を除去するための後処理を行う、光触媒性金属材料の製造方法である。
【００２０】
本発明において、光触媒塗料組成物を構成する部分被覆光触媒粉末については、光触媒活性を有する金属化合物の表面が光不活性無機物質で部分的に被覆されていることが必要である。
ここで、光触媒活性を有する金属化合物としては、代表的には酸化チタンであり、その他に酸化亜鉛、酸化タングステン、酸化鉄、チタン酸ストロンチウム等の半導体としての性質を有するものを挙げることができ、これらはその１種のみを単独で用いることができるほか、２種以上の混合物として用いることもできる。
【００２１】
また、上記金属化合物の表面を部分的に被覆する光不活性無機物質としては、それが光触媒活性による酸化、分解等の影響を受けないものであれば特に制限はなく、例えばシリカ、アルミナ、ジルコニア及びリン酸カルシウムから選ばれた１種又は２種以上の混合物を挙げることができ、耐薬品性、強度、水への分散性等を考慮すると、好ましくはシリカやリン酸カルシウムである。
【００２２】
そして、上記部分被覆光触媒粉末については、その平均粒子径が好ましくは５nm以上１００nm以下、より好ましくは１０nm以上５０nm以下であるのがよく、５nm未満では塗料組成物への分散が困難になってその取扱性が低下し、反対に、１００nmを超えると金属基材の表面に形成した光触媒塗膜の厚さが０．１μm以上０．２μm以下（＝100〜200nm）程度の薄さになると、塗膜表面に部分被覆光触媒粉末の粒子が露出してその固定が不十分になり、脱落し易くなり、また、単位面積当りの部分被覆光触媒粉末の粒子数が少なくなって光触媒活性が低下する。
【００２３】
このような部分被覆光触媒粉末の製造方法については、例えば特開平9-31,335号、特開平9-239,277号、特開平11-228,873号等の各公報に開示されており、また、その具体例としては、例えば、部分シリカ被覆酸化チタン（昭和電工社製商品名：F-1S02, F-4S05, F-4S20, F-6S10等）や部分リン酸カルシウム被覆酸化チタン（昭和電工社製商品名：F4-AP, F4-APS等）が例示される。
【００２４】
また、光触媒塗料組成物に用いる無機質造膜剤については、例えばシリカゾル、アルカリシリケート類、金属リン酸塩、金属アルコキシド等を例示でき、塗膜の耐水性や塗膜形成温度の観点から、好ましくはシリカゾルである。このシリカゾルは、水系溶剤に分散した微粒子状のケイ素酸化物であって常温硬化が可能であり、塗膜形成時にはシリカ粒子同士の表面にあるシラノール基同士の脱水反応により粒子間にシロキサン結合を形成するため、光触媒活性の影響を受け難い塗膜を形成できる。
【００２５】
この無機造膜剤として用いるシリカゾルの粒径については、シリカ粒子同士の結合に起因する塗膜の強度を考慮すると、平均粒子径が好ましくは１００nm以下、より好ましくは３０nm以下である。平均粒径が１００nmを超えると単位体積当りのシリカ粒子同士の結合点が少なくなり、結果として脆い光活性塗膜になる場合がある。
【００２６】
更に、光触媒塗料組成物に用いる水溶性有機高分子化合物については、例えば水溶性官能基（水酸基、アミノ基、カルボキシル基、スルホン基、アミド基、エーテル基等）を有するポリビニルアルコール、ポリアクリル酸、ポリメタクリル酸、ポリエチレングリコール、ポリアクリルアミド、ポリエチレンオキサイド、ポリスチレンスルホン酸等を例示でき、塗料の分散安定性の観点から、好ましくはグリコール類であり、これら水溶性有機高分子化合物はその1種のみを単独で使用できるほか、２種以上の混合物として用いることもできる。
【００２７】
上記グリコール類としては、例えばポリエチレングリコール、ポリプロピレングリコール等を例示でき、水への溶解度や熱分解温度の観点から、好ましくはポリエチレングリコールである。また、グリコール類の重量平均分子量については好ましくは１０００〜１０００００であり、この分子量が１０００未満では基材に対しての濡れ性が十分でなく、塗装時に塗料組成物の弾きが生じて均一な塗膜形成が困難になり、反対に、分子量が１０００００を越えると水系溶剤への溶解速度が小さくなり、塗料組成物の調製に長時間を要する。
【００２８】
ところで、アルミニウム材の陽極酸化皮膜は親水性を示すが、大気中に暴露すると表面が疎水性の物質で汚染され、次第に親水性が低下する。このため、水系溶剤のみの塗料組成物では陽極酸化皮膜の表面が汚染して疎水化した場合、この塗料組成物の塗装時に塗料の弾きが生じ、均一な塗布被膜を得ることが難しくなる場合がある。上記の水溶性高分子化合物は、一般に、その分子中に親水性を示す親水基（水溶性官能基）と疎水性を示す部分とが存在するため、陽極酸化皮膜の表面の親水性が低下した場合でも、水溶性有機高分子化合物の疎水性部分となじみ、塗料組成物は弾かれること無く均一に塗布可能になる。
【００２９】
本発明の光触媒塗料組成物においては、その組成は、全固形分に対して、部分被覆光触媒粉末が１質量%以上５０質量%以下、好ましくは１．５質量%以上２０質量%以下であり、無機質造膜剤が３０質量%以上８９質量%以下、好ましくは５０質量%以上８０質量%以下であり、また、水溶性有機高分子化合物が１０質量%以上５０質量%以下、好ましくは１０質量%以上３０質量%以下である。以下、これら各成分の濃度を固形分濃度という。
【００３０】
ここで、部分被覆光触媒粉末の固形分濃度が１質量%未満であると形成された光触媒塗膜中の含有量が少なくなり過ぎて十分な光触媒活性を得るのが困難になり、反対に、５０質量%を超えると光触媒塗膜中の無機質造膜剤の含有量が相対的に少なくなって部分被覆光触媒粉末が脱落し易くなるほか、脆くなって塗膜強度が不十分になる場合があり、更に、透明性を有する光触媒塗膜を得たい場合にはこの部分被覆光触媒粉末の固形分濃度を１〜１０質量%の範囲にするのがよい。
【００３１】
また、上記無機質造膜剤の固形分濃度が３０質量%未満であると部分被覆光触媒粉末が脱落し易くなるほか、脆くなって塗膜強度が不十分になる場合があり、反対に、８９質量%を超えると部分被覆光触媒粉末の含有量が少なくなり、充分な光触媒活性が得られなくなるほか、水溶性有機高分子化合物の含有量も低下し、塗料組成物の金属基材への濡れ性が低下し、均一な塗布が困難になる場合がある。
【００３２】
更に、上記水溶性有機高分子化合物の固形分濃度が１０質量%未満になると塗料組成物の金属基材への濡れ性を維持することが難しくなり、塗料組成物の弾きによって均一な塗膜の形成が難しくなり、反対に、５０質量%を超えると無機質造膜剤の固形分濃度が減少し、十分な塗膜強度が得られなくなる場合がある。透明性を有する光触媒塗膜を得たい場合にはこの水溶性有機高分子化合物の固形分濃度を１０〜３０質量%の範囲にするのがよい。
【００３３】
本発明の光触媒塗料組成物に用いる水系溶剤は、主に水であるが、金属基材との濡れ性をより向上させる必要がある場合には、例えばエタノール、プロパノール、イソプロパノール等のアルコール類や、アセトン、メチルエチルケトン等のケトン類や、フェノール、クレゾール、ハイドロキノン等のフェノール類等の水溶性有機溶剤、好ましくは常温で揮発性のある水溶性有機溶剤を適当な範囲で添加してもよい。エタノール、プロパノール、イソプロパノール、ブチルアルコール等のアルコール類は、常温揮発性であり、塗膜形成後に塗膜に残留せず、また、人体や環境への影響の少ない水溶性有機溶剤であって、特に好ましいものである。
【００３４】
なお、必要により、着色顔料として酸化チタン（ルチル型）、酸化亜鉛、酸化鉄（Fe2O3、FeO・OH）、チタンイエロー（TiO2, NiO, Sb2O3の三成分系酸化物）等の無機質顔料を添加してもよい。
【００３５】
本発明の上記光触媒塗料組成物を用いて水溶性有機高分子化合物が実質的に除去された光触媒性金属材料を製造するには、先ず、金属基材の表面に光触媒塗料組成物を塗布し、次いで乾燥させた後、形成された塗布被膜中の水溶性有機高分子化合物を除去するための後処理を行う。
【００３６】
ここで、金属基材の表面への光触媒塗料組成物の塗布は、例えば、スプレー塗装、ロールコート、ディップコート、刷毛塗り、スピンコート等の一般的な塗装方法を適用することが可能であり、好ましくはスプレー塗装、ロールコート、ディップコートである。
また、塗布後の塗料組成物の乾燥は、基本的には自然乾燥でよく、また、常温での送風乾燥、３００℃以下、好ましくは２５０℃以下での熱風乾燥等による乾燥でもよい。
【００３７】
金属基材の表面に光触媒塗料組成物を塗布し乾燥して得られた塗布被膜については、この塗布被膜中の水溶性有機高分子化合物を除去する目的で後処理を行うが、この後処理としては、例えばシャワー水洗や水洗槽での浸漬水洗等により水溶性有機高分子化合物を溶解除去する水洗処理、水溶性有機高分子化合物を分解又は蒸散させる加熱処理、雨水や河川水等により水溶性有機高分子化合物を溶解除去する自然水洗等の方法を挙げることができる。
【００３８】
なお、塗布被膜の後処理として加熱処理を行う場合、加熱温度については水溶性有機高分子化合物の分解温度や蒸発温度等を考慮して決定されるが、金属基材がアルミニウム材であり、また、水溶性有機高分子化合物としてポリエチレングリコール等のグリコール類を用いた場合には、好ましくは２００℃以上３００℃以下、より好ましくは２００℃以上２５０℃以下であるのがよい。２００℃未満ではポリエチレングリコールの分解温度が１８０℃程度であるために完全に分解除去できない場合があり、また、３００℃を超えると基材のアルミニウム材の強度が低下する虞があり、更に、アルミニウム材に陽極酸化皮膜が形成されている場合には、この加熱処理により陽極酸化皮膜の結晶水が取り除かれ、陽極酸化皮膜の体積が収縮して陽極酸化皮膜に亀裂や割れが生ずる虞があるので、加熱処理を２５０℃以下で行うのがよい。
【００３９】
本発明によって得られる光触媒性金属材料の光触媒塗膜については、好ましくはその膜厚が０．１μm以上０．２μm以下の範囲であるのがよい。０．１μm未満では均一で連続性のある光触媒塗膜を得るのが困難であり、充分な光触媒活性を発現させるのが難しくなり、反対に、０．２μmを超えると可視光線の干渉作用により虹色の干渉色を呈するようになるほか、部分被覆光触媒粉末の色彩が顕著になり、金属基材自体の色彩が損なわれる。
【００４０】
そして、本発明の上記光触媒塗料組成物が適用され、表面に光触媒塗膜が設けられる金属基材については、それがどのような種類の金属からなり、どのような形状のものであるか等について特に制限はなく、アルミニウム材を始めとして、例えば、鉄、ニッケル、コバルト、クロム、銅、亜鉛、マンガン、錫、チタン、マグネシウム、金、銀、白金等の金属又はその合金からなる板材、箔材、棒材、管材等やこれらを組み合わせた複雑形状の材料、部品、製品等を挙げることができるが、無機質造膜剤としてシリカゾルを用いた場合には常温硬化が可能なので、高温熱処理に適さないアルミニウム材について特に好適に適用することができる。
【００４１】
このアルミニウム材の表面に本発明の光触媒塗料組成物を適用し、光触媒塗膜を形成する場合、アルミニウム材の表面に直接に光触媒塗料組成物を適用して光触媒塗膜を形成してもよいが、光触媒塗料組成物とアルミニウム材との濡れ性向上、アルミニウム材の耐食性向上、アルミニウム材の着色・意匠性等の付与を目的に、先ずアルミニウム材の表面に親水性無機塗膜を形成し、その上に光触媒塗料組成物を適用して光触媒塗膜を形成してもよく、また、アルミニウム材の耐食性、耐水性、着色・意匠性、表面硬度、電気絶縁性等を向上させる目的で、先ずアルミニウム材の表面に陽極酸化皮膜を形成し、その上に光触媒塗料組成物を適用して光触媒塗膜を形成してもよく、更に、アルミニウム材の表面に陽極酸化皮膜を形成し、その上に親水性無機塗膜を形成し、更にその上に光触媒塗料組成物を適用して光触媒塗膜を形成してもよい。
【００４２】
このような目的でアルミニウム材の表面に形成する親水性無機塗膜としては、その上に形成される光触媒塗膜による光触媒活性の影響を受け難いものである必要があり、例えば、シリカゾル、シリコンアルコキシド、アルカリシリケート等を無機塗料成分を含有し、塗布硬化後にシリカを主成分とする親水性無機塗膜を形成するものが好適に用いられ、具体的にはスーパーセラ２１（株式会社京美製商品名）、アクアセラミクス（大生工業社製商品名）、Ｖハード#500（大日本塗料社製商品名）、ポーセリン#200（株式会社トウペ製商品名）等の親水性無機塗料を例示することができる。なお、親水性無機塗料には、塗膜形成後の初期の親水性が低く撥水性を示すものもあるが、この場合には紫外線照射や湿潤雰囲気に放置する等の親水化処理により塗膜表面を親水性にした後、基材として供するのが望ましい。
【００４３】
また、アルミニウム材の表面に形成する陽極酸化皮膜については、例えば硫酸、リン酸、シュウ酸、マロン酸等からなる電解液を用いた公知の陽極酸化処理によって行うことができる。また、ニッケル、コバルト、銅、錫、銀等の金属塩を含有する電解液を用いて陽極酸化皮膜の孔内にこれら金属を交流電解により析出させる公知の電解着色法により任意の色を呈色させることも可能である。更に、陽極酸化皮膜は沸騰水浸漬の他、アンモニア水、ケイ酸ナトリウム、酢酸ニッケル等の処理浴による封孔処理、水蒸気封孔処理等の公知の封孔処理によって封孔処理してもよく、これによって耐食性がより向上する。
【００４４】
上記アルミニウム材の表面に陽極酸化皮膜を形成する場合、その膜厚については５μm以上５０μm以下、好ましくは７μm以上２０μm以下であるのがよく、５μmより薄くなると十分な耐食性が発揮されない場合があり、反対に、５０μmを超えると陽極酸化皮膜に割れや剥離が起こる場合がある。
【００４５】
また、上記の親水性無機塗膜をアルミニウム材の表面に直接に形成する場合、その膜厚は１μm以上であることが好ましく、１μm未満では塗膜の水分透過によりアルミニウ材が腐食する場合がある。
更に、上記の親水性無機塗膜をアルミニウム材の表面に形成した陽極酸化皮膜の上に形成する場合、その膜厚は０．１μm以上であればよく、０．１μm未満では塗膜を均一に形成することが難しく、色彩の斑や十分な隠蔽性が得られない場合がある。
【００４６】
【発明の実施の形態】
以下、実施例及び比較例に基づいて本発明の好適な実施の形態を具体的に説明する。
【００４７】
［塗料の調製］
部分被覆光触媒粉末としてアパタイト被覆酸化チタンゾル（昭和電工社製商品名：F4-APS）を用い、光不活性無機物質による部分被覆無しの光触媒微粒子として酸化チタンゾル（昭和電工社製商品名：NTB-21）を用い、無機造膜剤としてシリカゾル（昭和ゴム社製商品名：MS-92）を用い、水溶性有機高分子化合物としてポリエチレングリコール（平均分子量：4000）を用い、また、水系溶剤として純水を用い、表１に示す割合で配合し、混合して実施例１〜６及び比較例１〜９の光触媒塗料組成物を調製した。
【００４８】
［アルミニウム片の調製］
また、厚さ１．０mmのアルミニウム合金板（JIS A5052）から１５０mm×７０mm×１．０mmの大きさのアルミニウム片を切り出し、脱脂・エッチング→水洗→中和→水洗を行う定法により前処理した後、以下に示す方法で各アルミニウム片の表面に表１に示す膜厚の陽極酸化皮膜及び／又は親水性無機塗膜を形成し、各実施例及び比較例に用いる試験片を調製するためのアルミニウム片とした。
【００４９】
（実施例１〜４及び比較例１〜８の試験片）
１５０g/Lの硫酸浴を用い、電流密度１．５A/dm2の定電流電解法により上記アルミニウム片の陽極酸化処理を行い、アルミニウム片の表面に膜厚４μm又は１０μmの陽極酸化皮膜を形成し、次いでこのアルミニウム片を沸騰純水中に３０分間浸漬して陽極酸化皮膜の封孔処理を行い、暗所の通常室内雰囲気下で１週間放置し、陽極酸化皮膜により表面処理された試験片とした。
【００５０】
（実施例５の試験片）
アルミニウム片の表面に上記と同様の陽極酸化処理を行って膜厚１０μmの陽極酸化皮膜を形成した後、バーコーターを用いて比較例８に示す光触媒無添加の塗料組成物（親水性無機塗料）を塗布し、陽極酸化皮膜の上に膜厚２μmの親水性無機塗膜を形成し、暗所の通常室内雰囲気下で１週間放置し、表面処理された試験片とした。
【００５１】
（実施例６及び比較例９の試験片）
バーコーターを用いてアルミニウム片の表面に、陽極酸化処理を施すことなく、直接に比較例８に示す光触媒無添加の塗料組成物（親水性無機塗料）を塗布し、表１に示す膜厚１．５μm又は０．５μmの親水性無機塗膜を形成し、暗所の通常室内雰囲気下で１週間放置し、表面処理された試験片とした。
【００５２】
［塗布被膜の形成］
比較例７の試験片を除く各実施例及び比較例の試験片には、バーコーターを用いてその表面に各実施例及び比較例の光触媒塗料組成物を塗布量３g/m2となるように塗布し、室温で乾燥して塗布被膜を形成した後、暗所で１２時間放置し、表１に示す膜厚の塗布被膜を有する試験片を調製した。また、比較例７の試験片については、比較例７の光触媒塗料組成物を塗布量８g/m2となるように塗布し、上記と同様にして膜厚０．３μmの塗布被膜を有する試験片とした。
【００５３】
［光触媒塗膜の形成］
実施例１、実施例３〜６及び比較例１〜９の各試験片については、純水５L中に１時間浸漬した後、更に純水の流水で洗浄し、５０℃温風乾燥機で１時間乾燥し、表面に光触媒塗膜が形成された試験片とした。
また、実施例２の試験片については、上記塗布被膜が形成された試験片をオーブン中で２００℃、１０分間加熱処理し、表面に光触媒塗膜が形成された試験片とした。
【００５４】
【表１】
［外観観察］
各実施例及び比較例の試験片について、その外観を蛍光灯下で目視観察し、表面に陽極酸化皮膜のみを有するアルミニウム片と比較し、光触媒塗膜の透明性や、白濁及び干渉色の有無を確認した。結果を表２に示す。
【００５６】
［密着性］
碁盤目密着性試験（JIS K5400）に基づき、光触媒塗膜の密着性を評価した。碁盤目間隔は１mmで試験片にキズを付け、テープ剥離後の塗膜剥離を観察し、○：塗膜剥離が無いもの、及び、×：塗膜剥離が１点以上あるものの評価基準で判定した。結果を表２に示す。
【００５７】
［促進耐候性試験］
サンシャインカ−ボンアーク灯式耐候性試験機を用い、JIS K5400に準じて促進耐候性試験を行い、３０００時間試験後の塗膜白亜化を未試験の比較板と比較し、○：特に白化していないもの、及び、×：白化の認められるものの評価基準で評価した。結果を表２に示す。
【００５８】
［耐食性試験］
JIS H8602に準じてキャス試験２４時間を行い、試験後の各試験片の孔食発生状況をレイティングナンバー標準図と比較してレイティングナンバーを求め、○：レイティングナンバー９．５以上、及び、×：レイティングナンバー９．５未満の評価基準で評価した。結果を表２に示す。
【００５９】
［光触媒活性の評価］
光触媒塗膜形成後と促進耐候性試験後の各試験片を暗所で７日間放置した後、接触角計（協和界面科学社製 型式CA-A）を用い、次のようにして水の接触角を測定した。すなわち、注射器の針先端に直径１．５mmの水滴を形成し、この水滴を水平に置かれた試験片の光触媒塗膜表面に付着させ、水滴と試験片との接触面の中心点を通る垂線が水滴上部と交わる交点を水滴頂上点とし、水滴端部の試験片との接触点と上記水滴頂上点を結ぶ直線と試験片表面で形成される角度を測定し、この角度の２倍の値を水の接触角測定値とした。この方法で各試験片につき５点づつ接触角を測定し、各試験片の接触角の平均値を求め、各試験片の初期の接触角とした。結果の詳細を表３に示す。
【００６０】
次に、各試験片の光触媒塗膜表面にオレイン酸を塗布し、暗所で１時間放置した後、水洗して過剰なオレイン酸を洗い流し、次いで５０℃の温風で１時間乾燥した後、上記と同様にして接触角を測定し、各試験片の汚染時の接触角とした。結果の詳細を表３に示す。
【００６１】
その後、暗室に試験片を設置し、２灯の10W-ブラックライトにより各試験片の表面に紫外線照射を行った。このときの試験片表面における紫外線強度は１mW/cm2とした。紫外線照射開始から２時間、４時間、２４時間後に上記と同様にしてそれぞれ接触角を測定し、○：紫外線照射により水の接触角が１０度以下になったもの、及び、×：水の接触角が１０度以下にならなかったものの評価基準で光触媒活性を評価した。結果の詳細を表３に示す。
【００６２】
【表２】
【表３】
上記表２の結果から明らかなように、本発明の実施例１〜６により作成された試験片は、何れも基材との濡れ性、塗膜剥離、親水性、耐候性、耐食性において良好な結果を示しており、これに対して、比較例１〜９の試験片は、基材との濡れ性、塗膜剥離、親水性、耐候性、耐食性のいずれかにおいて問題が生じている。
【００６５】
【発明の効果】
本発明の光触媒塗料組成物によれば、アルミニウム材等の金属基材の表面に塗布し、チョーキング現象がなくて長期間の耐久性を有する光触媒塗膜を容易に形成することができる。
また、本発明の光触媒性金属材料は、優れた光触媒活性を有するだけでなく、チョーキング現象がなくて長期間の耐久性を有するので、建築材料、車両外装材、パネル製品、道路付帯設備等の多くの用途に好適に用いることができるものである。更に、本発明の光触媒性金属材料の製造方法によれば、特殊な塗装設備や焼付け炉等を必要とすることなく、光触媒活性及び耐久性に優れた光触媒性金属材料を安価に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal substrate, a photocatalyst coating composition for a metal substrate for forming a photocatalyst coating film by coating on the surface of an aluminum material made of aluminum or an aluminum alloy, although not particularly limited, and the present invention The present invention relates to a photocatalytic metal material obtained by using and a method for producing the photocatalytic metal material.
[0002]
[Prior art]
[Patent Document 1]
JP 2000-254,518
[Patent Document 2]
JP 2001-10,877
[Patent Document 3]
JP 2001-98,187
[Patent Document 4]
Japanese Patent No. 3,210,544
[Patent Document 5]
Japanese Patent No. 3,210,546
[Patent Document 6]
JP-A-10-174,883
[0003]
A metal compound having photocatalytic activity typified by titanium oxide (hereinafter sometimes simply referred to as “photocatalyst”) can decompose various harmful substances using light energy, and can also be used on the surface of various products. When applied, it attracts attention in many applications because it makes the surface of the substrate hydrophilic so that dirt attached to the surface can be easily removed.
[0004]
In order to efficiently express such photocatalytic activity on the surface of the product substrate, first, a technique for securely fixing the photocatalyst to the surface of the product substrate is important. A coating composition is prepared by blending a binder resin for fixing and forming a coating film. The coating composition is applied to the substrate surface to form a coating film in which fine particles of photocatalyst are dispersed on the substrate surface. Thus, a method for imparting a photocatalytic function to the surface of a substrate of a product has been performed.
[0005]
However, the photocatalytic activity of the photocatalyst is due to the occurrence of oxidation-reduction reaction, active oxygen, etc. on the surface due to light irradiation, so prepare a coating composition using an organic resin binder resin, When this coating composition is applied to form a photocatalytic coating film on the substrate surface, the binder resin forming the photocatalytic coating film is oxidized or decomposed by the oxidizing action of active oxygen, and the binder resin disappears. As a result, the photocatalyst coating film cannot maintain its form, and a so-called choking phenomenon in which the photocatalyst falls off appears.
[0006]
Therefore, conventionally, as a countermeasure against the choking phenomenon of the photocatalyst coating film, a method using an inorganic binder obtained from a metal alkoxide or polysiloxane has been studied. However, the method using this inorganic binder has a slow coating formation reaction rate, and a large volume reduction during film formation tends to cause cracks in the formed photocatalytic coating film. Occasionally, there is a problem that the coating tends to whiten when it comes into contact with rainwater.
[0007]
Also, a method of forming a photocatalytic coating film by a sol-gel method using a metal alkoxide has been proposed. In this method, it is necessary to treat at a high temperature of at least 300 ° C., for example, aluminum or an aluminum alloy is used. When an aluminum material is used, if heat treatment is performed at such a high temperature, it may not be applicable depending on the type of metal substrate, such as causing a decrease in strength of the aluminum material itself.
[0008]
Furthermore, as a countermeasure against the choking phenomenon of the photocatalyst coating film, a part of the photocatalyst particle surface is partially covered with a photoinert inorganic substance so that the photocatalyst does not come into direct contact with the binder, thereby preventing deterioration of the binder. Attempts have been made and various methods have been proposed.
[0009]
For example, Japanese Patent Laid-Open No. 2000-254,518 examines the optimum conditions for the titanium content and the primary particle size in a composite oxide of titanium and silicon and / or zirconium, and attempts to apply them to paints.
However, according to Examples and Reference Examples using an organic resin binder, titanium oxide for pigments showing almost no photocatalytic activity has almost no falling off of titanium oxide, whereas titanium oxide showing photocatalytic activity is used. In these examples, the detachment of titanium oxide was observed, and the deterioration of the organic binder was not sufficiently suppressed.
[0010]
JP-A-2001-10877 discloses a photocatalyst coating composition that contains photocatalyst fine particles surface-treated with silica and colloidal silica, can be easily applied to a thin film at room temperature, and has high transparency. Things are listed.
However, this photocatalyst coating composition is intended for cement-based base materials such as concrete and mortar, and its application to metal materials has not been studied at all.
[0011]
Furthermore, JP-A-2001-98,187 discloses a photocatalytic titanium oxide particle surface-treated with a coating film-forming element composed of an alkali metal silicate that is cured to form a coating film, inorganic oxide particles, and / or precursors thereof. A photocatalytic hydrophilic coating composition having a pH of 5 to 9 is disclosed.
However, this photocatalytic hydrophilic coating composition is also intended to be applied to the surface of a substrate that requires transparency, such as glass, lenses, and mirrors, and its application to metal materials has not been studied at all.
[0012]
Further, in Japanese Patent No. 3,210,544, an anodized film is formed on the surface of a base material made of an aluminum material, and a sputtering method, a thermal spray method, a laser ablation method, a sol-gel method, a plating method, etc. are formed on the anodized film. An antibacterial / anti-rust aluminum building material coated with a thin film having a film thickness of 1 μm or less having photocatalytic activity is disclosed.
However, in this aluminum building material, when a photocatalyst coating film is formed, a dedicated device, a baking treatment, and the like are necessary, so that on-site construction is difficult and repair work is also difficult.
[0013]
Furthermore, in Japanese Patent No. 3,210,546, an anodized film is formed on the surface of a base material made of an aluminum material, and a coating composition containing a photocatalyst is applied on the anodized film by electrodeposition coating or electrostatic coating. An antibacterial and anti-bacterial building material is disclosed.
However, even in this building material, when a photocatalyst coating film is formed, a dedicated device or baking treatment is necessary, so that it is difficult to perform on-site construction, and repair work is difficult. In the case of using a paint component of the system, deterioration due to photocatalytic activity is inevitable.
[0014]
Furthermore, JP-A-10-174,883 discloses that a porous film such as an anodic oxide film or boehmite film is formed on the surface of a base material made of an aluminum material, and has photocatalytic activity by means such as immersion in the porous film. It describes that a titanium oxide sol is chemically adsorbed, washed with water and dried by heating to produce an aluminum material having a photocatalytic function. This method also requires a treatment tank for immersing the substrate having a porous film in the titanium oxide sol solution, and also requires a heating device for heating and drying, which is difficult to perform on-site. Repair work is also difficult.
[0015]
[Problems to be solved by the invention]
Therefore, the present inventor has intensively studied a photocatalyst coating composition that can be easily applied to the surface of a metal substrate such as an aluminum material and can easily form a photocatalytic coating film without a choking phenomenon. Using a photocatalyst coating composition containing a partially coated photocatalyst powder partially coated with an inorganic substance, an inorganic film-forming agent, and a water-soluble organic polymer compound, and applying it to a water-soluble coating film The inventors have found that the object can be easily achieved by performing a post-treatment for removing the organic polymer compound, thereby completing the present invention.
[0016]
Accordingly, an object of the present invention is to provide a photocatalyst coating composition that can be easily applied to the surface of a metal substrate such as an aluminum material to form a photocatalyst coating film without a choking phenomenon.
Another object of the present invention is to provide a photocatalytic metal material having a photocatalytic coating film free from choking on the surface of a metal substrate such as an aluminum material.
Furthermore, another object of the present invention is to provide a method for producing a photocatalytic metal material for producing a photocatalytic metal material having a photocatalytic coating film free from choking on the surface of a metal substrate such as an aluminum material. It is in.
[0017]
That is, the present invention is a photocatalyst coating composition that is applied to the surface of a metal substrate to form a photocatalyst coating film on the surface of the metal substrate, and has photocatalytic activity with respect to the total solid content in the aqueous solvent. 1 to 50% by mass of a partially coated photocatalyst powder obtained by partially coating the surface of a metal compound with a photoinert inorganic substance, and 30 to 89% by mass of an inorganic film-forming agent, and A weight average molecular weight of 1,000 to 100,000, which comprises one or more selected from polyethylene glycol or polypropylene glycol and imparts wettability to a metal substrate. It is a photocatalyst coating composition for metal substrates, each containing a water-soluble organic polymer compound in a proportion of 10 to 50% by mass.
[0018]
Further, the present invention is obtained by applying the above-mentioned photocatalyst coating composition to the surface of a metal substrate and then drying it, and then substantially removing the water-soluble organic polymer compound in the formed coating film. Photocatalytic metal material.
[0019]
Furthermore, the present invention performs the post-treatment for removing the water-soluble organic polymer compound in the formed coating film after coating the photocatalyst coating composition on the surface of the metal substrate and then drying it. This is a method for producing a photocatalytic metal material.
[0020]
In the present invention, for the partially coated photocatalyst powder constituting the photocatalyst coating composition, it is necessary that the surface of the metal compound having photocatalytic activity is partially coated with a photoinert inorganic substance.
Here, the metal compound having photocatalytic activity is typically titanium oxide, and other examples include those having properties as semiconductors such as zinc oxide, tungsten oxide, iron oxide, strontium titanate, These can be used alone or in a mixture of two or more.
[0021]
The photoinert inorganic substance that partially covers the surface of the metal compound is not particularly limited as long as it is not affected by oxidation, decomposition, etc. due to photocatalytic activity. For example, silica, alumina, zirconia And one or a mixture of two or more selected from calcium phosphate. In view of chemical resistance, strength, dispersibility in water, etc., silica and calcium phosphate are preferred.
[0022]
For the partially coated photocatalyst powder, the average particle size is preferably 5 nm or more and 100 nm or less, more preferably 10 nm or more and 50 nm or less. If the particle diameter is less than 5 nm, dispersion into the coating composition becomes difficult. On the other hand, when the thickness of the photocatalyst coating film formed on the surface of the metal substrate becomes as thin as 0.1 μm or more and 0.2 μm or less (= 100 to 200 nm) when the thickness exceeds 100 nm, The particles of the partially coated photocatalyst powder are exposed on the film surface, and the fixation thereof becomes insufficient, and the particles are easily detached. Further, the number of particles of the partially coated photocatalyst powder per unit area is reduced and the photocatalytic activity is lowered.
[0023]
The method for producing such partially coated photocatalyst powder is disclosed in, for example, JP-A-9-31,335, JP-A-9-239,277, JP-A-11-228,873, etc., and specific examples thereof Is, for example, partially silica-coated titanium oxide (trade names manufactured by Showa Denko KK: F-1S02, F-4S05, F-4S20, F-6S10, etc.) and partially calcium phosphate-coated titanium oxide (trade name manufactured by Showa Denko KK: F4- AP, F4-APS, etc.).
[0024]
Examples of the inorganic film-forming agent used in the photocatalyst coating composition can include, for example, silica sol, alkali silicates, metal phosphates, metal alkoxides, etc., preferably from the viewpoint of the water resistance of the coating film and the coating film forming temperature. Silica sol. This silica sol is a particulate silicon oxide dispersed in an aqueous solvent and can be cured at room temperature. During coating film formation, siloxane bonds are formed between the particles by the dehydration reaction between silanol groups on the surface of the silica particles. Therefore, a coating film that is hardly affected by the photocatalytic activity can be formed.
[0025]
Regarding the particle size of the silica sol used as the inorganic film-forming agent, the average particle size is preferably 100 nm or less, more preferably 30 nm or less, considering the strength of the coating film resulting from the bonding between the silica particles. When the average particle diameter exceeds 100 nm, the number of bonding points between silica particles per unit volume decreases, and as a result, a brittle photoactive coating film may be obtained.
[0026]
Furthermore, for the water-soluble organic polymer compound used in the photocatalyst coating composition, for example, polyvinyl alcohol having a water-soluble functional group (hydroxyl group, amino group, carboxyl group, sulfone group, amide group, ether group, etc.), polyacrylic acid, Polymethacrylic acid, polyethylene glycol, polyacrylamide, polyethylene oxide, polystyrene sulfonic acid and the like can be exemplified, and from the viewpoint of dispersion stability of the paint, glycols are preferable, and these water-soluble organic polymer compounds are only one of them. It can be used alone or in a mixture of two or more.
[0027]
Examples of the glycols include polyethylene glycol and polypropylene glycol, and polyethylene glycol is preferable from the viewpoint of water solubility and thermal decomposition temperature. The weight average molecular weight of the glycols is preferably 1000 to 100,000. If the molecular weight is less than 1000, the wettability with respect to the substrate is not sufficient, and the coating composition is repelled during coating, resulting in uniform coating. On the other hand, when the molecular weight exceeds 100,000, the dissolution rate in an aqueous solvent decreases, and it takes a long time to prepare a coating composition.
[0028]
By the way, although the anodic oxide film of an aluminum material shows hydrophilicity, when it exposes to air | atmosphere, the surface will be contaminated with a hydrophobic substance, and hydrophilicity will fall gradually. For this reason, when the surface of the anodized film is contaminated and hydrophobicized with a paint composition containing only an aqueous solvent, the paint may be repelled when the paint composition is applied, and it may be difficult to obtain a uniform coating film. is there. The above water-soluble polymer compound generally has a hydrophilic group (water-soluble functional group) having a hydrophilic property and a hydrophobic portion in the molecule, so that the hydrophilicity of the surface of the anodized film is lowered. Even in such a case, the coating composition can be uniformly applied without being repelled by blending with the hydrophobic portion of the water-soluble organic polymer compound.
[0029]
In the photocatalyst coating composition of the present invention, the composition of the partially coated photocatalyst powder is 1% by mass or more and 50% by mass or less, preferably 1.5% by mass or more and 20% by mass or less, based on the total solid content. The inorganic film-forming agent is 30% by mass to 89% by mass, preferably 50% by mass to 80% by mass, and the water-soluble organic polymer compound is 10% by mass to 50% by mass, preferably 10% by mass. The content is 30% by mass or less. Hereinafter, the concentration of each of these components is referred to as the solid content concentration.
[0030]
Here, when the solid content concentration of the partially coated photocatalyst powder is less than 1% by mass, the content in the formed photocatalyst coating film becomes too small, and it becomes difficult to obtain sufficient photocatalytic activity. If it exceeds mass%, the content of the inorganic film-forming agent in the photocatalyst coating film becomes relatively small, and the partially coated photocatalyst powder tends to fall off, and the coating film strength may become insufficient due to brittleness. Furthermore, when it is desired to obtain a photocatalyst coating film having transparency, the solid content concentration of the partially coated photocatalyst powder is preferably in the range of 1 to 10% by mass.
[0031]
Further, when the solid content concentration of the inorganic film-forming agent is less than 30% by mass, the partially coated photocatalyst powder is liable to fall off and may become brittle and the coating film strength may be insufficient. If it exceeds%, the content of the partially coated photocatalyst powder will be reduced and sufficient photocatalytic activity will not be obtained, and the content of the water-soluble organic polymer compound will also be reduced, so that the wettability of the coating composition to the metal substrate will be reduced. It may decrease, and uniform application may be difficult.
[0032]
Furthermore, when the solid content concentration of the water-soluble organic polymer compound is less than 10% by mass, it becomes difficult to maintain the wettability of the coating composition to the metal substrate, and a uniform coating film is formed by repelling the coating composition. On the other hand, when it exceeds 50% by mass, the solid content concentration of the inorganic film-forming agent decreases, and sufficient coating strength may not be obtained. When it is desired to obtain a photocatalyst coating film having transparency, the solid content concentration of the water-soluble organic polymer compound is preferably in the range of 10 to 30% by mass.
[0033]
The aqueous solvent used in the photocatalyst coating composition of the present invention is mainly water, but when it is necessary to further improve the wettability with a metal substrate, for example, alcohols such as ethanol, propanol, isopropanol, Water-soluble organic solvents such as ketones such as acetone and methyl ethyl ketone, and phenols such as phenol, cresol, and hydroquinone, preferably water-soluble organic solvents that are volatile at room temperature, may be added in an appropriate range. Alcohols such as ethanol, propanol, isopropanol, and butyl alcohol are water-soluble organic solvents that are volatile at room temperature, do not remain on the coating film after formation, and have little impact on the human body and the environment. It is preferable.
[0034]
In addition, if necessary, titanium oxide (rutile type), zinc oxide, iron oxide (Fe 2 O Three , FeO · OH), titanium yellow (TiO 2 , NiO, Sb 2 O Three An inorganic pigment such as a three-component oxide) may be added.
[0035]
In order to produce a photocatalytic metal material from which the water-soluble organic polymer compound is substantially removed using the photocatalyst coating composition of the present invention, first, a photocatalytic coating composition is applied to the surface of a metal substrate, Next, after drying, a post-treatment for removing the water-soluble organic polymer compound in the formed coating film is performed.
[0036]
Here, the application of the photocatalyst coating composition to the surface of the metal substrate can be applied, for example, a general coating method such as spray coating, roll coating, dip coating, brush coating, spin coating, Spray coating, roll coating, and dip coating are preferred.
Further, the coating composition after application may be dried basically by natural drying, or may be drying by blowing at normal temperature, hot air drying at 300 ° C. or lower, preferably 250 ° C. or lower.
[0037]
The coating film obtained by applying the photocatalyst coating composition to the surface of the metal substrate and drying is subjected to a post-treatment for the purpose of removing the water-soluble organic polymer compound in the coating film. For example, a water-washing treatment for dissolving and removing water-soluble organic polymer compounds by shower water washing or immersion water washing in a water-washing tank, a heat treatment for decomposing or evaporating water-soluble organic polymer compounds, water-soluble organic polymers by rainwater or river water, etc. A method such as natural water washing for dissolving and removing the polymer compound can be mentioned.
[0038]
When heat treatment is performed as a post-treatment of the coating film, the heating temperature is determined in consideration of the decomposition temperature, evaporation temperature, etc. of the water-soluble organic polymer compound, but the metal substrate is an aluminum material, When a glycol such as polyethylene glycol is used as the water-soluble organic polymer compound, it is preferably 200 ° C. or higher and 300 ° C. or lower, more preferably 200 ° C. or higher and 250 ° C. or lower. If it is less than 200 ° C., the decomposition temperature of polyethylene glycol is about 180 ° C., so that it may not be completely decomposed and removed. If it exceeds 300 ° C., the strength of the aluminum material of the substrate may be lowered. If an anodized film is formed on the material, the crystallization of the anodized film is removed by this heat treatment, and the volume of the anodized film may shrink and cracks or cracks may occur in the anodized film. The heat treatment is preferably performed at 250 ° C. or lower.
[0039]
The photocatalytic coating film of the photocatalytic metal material obtained by the present invention preferably has a thickness in the range of 0.1 μm or more and 0.2 μm or less. If the thickness is less than 0.1 μm, it is difficult to obtain a uniform and continuous photocatalytic coating film, and it becomes difficult to develop sufficient photocatalytic activity. In addition to exhibiting interference colors, the color of the partially coated photocatalyst powder becomes significant, and the color of the metal substrate itself is impaired.
[0040]
And about the metal base material to which the said photocatalyst coating composition of this invention is applied and a photocatalyst coating film is provided on the surface, what kind of metal it is, what kind of shape etc. There is no particular limitation, for example, aluminum, and other materials such as iron, nickel, cobalt, chromium, copper, zinc, manganese, tin, titanium, magnesium, gold, silver, platinum, etc. , Bar materials, pipe materials, etc., and complex shapes of materials, parts, products, etc. can be mentioned, but when silica sol is used as an inorganic film-forming agent, room temperature curing is possible and it is not suitable for high temperature heat treatment The aluminum material can be particularly preferably applied.
[0041]
When the photocatalyst coating composition of the present invention is applied to the surface of the aluminum material to form a photocatalyst coating film, the photocatalyst coating composition may be formed by directly applying the photocatalyst coating composition to the surface of the aluminum material. First, a hydrophilic inorganic coating film is formed on the surface of the aluminum material in order to improve the wettability between the photocatalyst coating composition and the aluminum material, to improve the corrosion resistance of the aluminum material, and to impart the coloring and design properties of the aluminum material. The photocatalyst coating composition may be applied to form a photocatalyst coating film, and aluminum is first used for the purpose of improving the corrosion resistance, water resistance, coloring / design properties, surface hardness, electrical insulation, etc. of the aluminum material. An anodized film may be formed on the surface of the material, and a photocatalyst coating composition may be applied thereon to form a photocatalyst film, and further, an anodized film may be formed on the surface of the aluminum material. Forming an aqueous inorganic coating film may be formed photocatalyst coating film and further applying the photocatalytic coating composition thereon.
[0042]
The hydrophilic inorganic coating film formed on the surface of the aluminum material for such a purpose must be hardly affected by the photocatalytic activity of the photocatalytic coating film formed thereon, for example, silica sol, silicon alkoxide In addition, an alkali silicate or the like containing an inorganic paint component and forming a hydrophilic inorganic coating film mainly composed of silica after coating and curing is preferably used. Specifically, Super Sera 21 (trade name, manufactured by Kyomi Corporation) ), Aqua Ceramics (trade name, manufactured by Taisei Kogyo Co., Ltd.), V Hard # 500 (trade name, manufactured by Dainippon Paint Co., Ltd.), Porcelain # 200 (trade name, manufactured by Toupe Co., Ltd.), and the like. . Some hydrophilic inorganic paints have low initial hydrophilicity after film formation and show water repellency. In this case, the surface of the paint film is treated by hydrophilic treatment such as ultraviolet irradiation or leaving it in a humid atmosphere. It is desirable to use as a base material after making it hydrophilic.
[0043]
Moreover, about the anodic oxide film formed on the surface of an aluminum material, it can carry out by the well-known anodic oxidation process using the electrolyte solution which consists of sulfuric acid, phosphoric acid, oxalic acid, malonic acid etc., for example. In addition, using an electrolytic solution containing a metal salt such as nickel, cobalt, copper, tin, silver, etc., any color is produced by a known electrolytic coloring method in which these metals are deposited in the pores of the anodized film by alternating current electrolysis. It is also possible to make it. Furthermore, the anodized film may be subjected to a sealing treatment by a known sealing treatment such as a sealing treatment with a treatment bath such as ammonia water, sodium silicate, nickel acetate, etc., in addition to immersion in boiling water, This further improves the corrosion resistance.
[0044]
When an anodized film is formed on the surface of the aluminum material, the film thickness is 5 μm or more and 50 μm or less, preferably 7 μm or more and 20 μm or less. If the thickness is less than 5 μm, sufficient corrosion resistance may not be exhibited. On the other hand, if it exceeds 50 μm, the anodized film may be cracked or peeled off.
[0045]
Moreover, when forming said hydrophilic inorganic coating film directly on the surface of an aluminum material, it is preferable that the film thickness is 1 micrometer or more, and when less than 1 micrometer, an aluminum material may corrode by the water permeation of a coating film. .
Furthermore, when the above hydrophilic inorganic coating film is formed on the anodized film formed on the surface of the aluminum material, the film thickness should be 0.1 μm or more, and if it is less than 0.1 μm, the coating film should be uniform. It is difficult to form and color spots and sufficient concealment may not be obtained.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.
[0047]
[Preparation of paint]
Apatite-coated titanium oxide sol (trade name: F4-APS, manufactured by Showa Denko KK) is used as the partially coated photocatalyst powder, and titanium oxide sol (trade name, manufactured by Showa Denko KK: NTB-21) is used as photocatalyst fine particles that are not partially coated with a photoinert inorganic substance. ), Silica sol (trade name: MS-92 manufactured by Showa Rubber Co., Ltd.) as the inorganic film-forming agent, polyethylene glycol (average molecular weight: 4000) as the water-soluble organic polymer compound, and pure water as the aqueous solvent The photocatalyst coating compositions of Examples 1 to 6 and Comparative Examples 1 to 9 were prepared by mixing at a ratio shown in Table 1 and mixing.
[0048]
[Preparation of aluminum pieces]
After cutting a piece of aluminum of 150 mm x 70 mm x 1.0 mm from an aluminum alloy plate (JIS A5052) with a thickness of 1.0 mm, and pre-treating it according to a conventional method of degreasing, etching, water washing, neutralization and water washing Aluminum for preparing test pieces used in the examples and comparative examples by forming an anodic oxide film and / or hydrophilic inorganic coating film having the thickness shown in Table 1 on the surface of each aluminum piece by the following method It was a piece.
[0049]
(Test pieces of Examples 1 to 4 and Comparative Examples 1 to 8)
Using a 150 g / L sulfuric acid bath, current density 1.5 A / dm 2 The aluminum piece is anodized by the constant current electrolysis method, and an anodized film having a film thickness of 4 μm or 10 μm is formed on the surface of the aluminum piece. Then, the aluminum piece is immersed in boiling pure water for 30 minutes. The oxide film was subjected to sealing treatment, and left for 1 week in a normal room atmosphere in a dark place to obtain a test piece surface-treated with an anodized film.
[0050]
(Test piece of Example 5)
The surface of the aluminum piece is subjected to the same anodic oxidation treatment as described above to form an anodic oxide film having a thickness of 10 μm, and then a coating composition containing no photocatalyst shown in Comparative Example 8 using a bar coater (hydrophilic inorganic coating) Was applied to form a hydrophilic inorganic coating film having a thickness of 2 μm on the anodized film, and left for 1 week in a normal room atmosphere in a dark place to obtain a surface-treated test piece.
[0051]
(Test pieces of Example 6 and Comparative Example 9)
Using a bar coater, the coating composition (hydrophilic inorganic coating) containing no photocatalyst shown in Comparative Example 8 was directly applied to the surface of the aluminum piece without anodizing, and the film thickness 1 shown in Table 1 was applied. A hydrophilic inorganic coating film of 5 μm or 0.5 μm was formed and left for 1 week in a normal room atmosphere in a dark place to obtain a surface-treated test piece.
[0052]
[Formation of coating film]
The test piece of each Example and Comparative Example except the test piece of Comparative Example 7 was coated with the photocatalyst coating composition of each Example and Comparative Example on its surface using a bar coater at a coating amount of 3 g / m. 2 After coating to form a coating film by drying at room temperature, it was allowed to stand in the dark for 12 hours to prepare a test piece having a coating film with a film thickness shown in Table 1. For the test piece of Comparative Example 7, the coating amount of the photocatalyst coating composition of Comparative Example 7 was 8 g / m. 2 In the same manner as described above, a test piece having a coating film thickness of 0.3 μm was obtained.
[0053]
[Formation of photocatalytic coating film]
About each test piece of Example 1, Examples 3-6, and Comparative Examples 1-9, after immersing in 5 L of pure water for 1 hour, it wash | cleans with the pure water flowing further, and is 50 degreeC warm air dryer 1 A test piece having a photocatalyst coating film formed on the surface thereof after drying for a time was obtained.
Moreover, about the test piece of Example 2, the test piece in which the said coating film was formed was heat-processed at 200 degreeC for 10 minute (s) in oven, and it was set as the test piece by which the photocatalyst coating film was formed on the surface.
[0054]
[Table 1]
[Appearance observation]
About the test piece of each Example and Comparative Example, the appearance is visually observed under a fluorescent lamp, and compared with an aluminum piece having only an anodized film on the surface, the photocatalyst coating film is transparent, white turbid, and presence of interference colors It was confirmed. The results are shown in Table 2.
[0056]
[Adhesion]
Based on the cross-cut adhesion test (JIS K5400), the adhesion of the photocatalyst coating film was evaluated. The grid spacing is 1 mm, scratches the test piece, and observes the peeling of the coating film after peeling the tape. ○: No peeling of the coating film, ×: Evaluation based on the evaluation criteria of one or more peeling coating films did. The results are shown in Table 2.
[0057]
[Accelerated weather resistance test]
Using a sunshine carbon-arc arc type weathering tester, an accelerated weathering test was performed according to JIS K5400, and the whitening of the paint film after 3000 hours test was compared with an untested comparison board. Evaluation was made based on the evaluation criteria for those not present and x: whitening was observed. The results are shown in Table 2.
[0058]
[Corrosion resistance test]
A casting test was performed for 24 hours according to JIS H8602, and the pitting corrosion occurrence state of each test piece after the test was compared with the rating number standard chart to obtain the rating number. ○: Rating number 9.5 or more and ×: Evaluation was made based on an evaluation standard having a rating number of less than 9.5. The results are shown in Table 2.
[0059]
[Evaluation of photocatalytic activity]
After each photocatalyst film is formed and after the accelerated weathering test, each test piece is left in the dark for 7 days, and then contacted with water using a contact angle meter (model Kyowa Interface Science Co., Ltd. Model CA-A) as follows. The corner was measured. That is, a water droplet having a diameter of 1.5 mm is formed at the tip of a syringe needle, and this water droplet is attached to the surface of the photocatalyst coating film of a horizontally placed test piece, and a perpendicular line passing through the center point of the contact surface between the water drop and the test piece. Measure the angle formed between the point of contact with the test piece at the end of the water drop and the straight line connecting the top point of the water drop and the surface of the test piece, and the value that is twice this angle. Was the contact angle measurement of water. By this method, the contact angle of 5 points was measured for each test piece, the average value of the contact angles of each test piece was determined, and the initial contact angle of each test piece was obtained. Details of the results are shown in Table 3.
[0060]
Next, after applying oleic acid to the photocatalyst coating surface of each test piece and leaving it in the dark for 1 hour, washing with water to wash away excess oleic acid, and then drying with hot air at 50 ° C. for 1 hour, The contact angle was measured in the same manner as described above, and the contact angle at the time of contamination of each test piece was determined. Details of the results are shown in Table 3.
[0061]
Then, the test piece was installed in the dark room, and the ultraviolet ray was irradiated to the surface of each test piece with two 10W-black lights. The UV intensity on the surface of the test piece at this time is 1 mW / cm 2 It was. 2 hours, 4 hours, and 24 hours after the start of UV irradiation, the contact angles were measured in the same manner as described above. ○: The contact angle of water became 10 degrees or less by UV irradiation, and X: Contact of water The photocatalytic activity was evaluated based on the evaluation criteria for the angle that did not become 10 degrees or less. Details of the results are shown in Table 3.
[0062]
[Table 2]
[Table 3]
As is clear from the results of Table 2 above, the test pieces prepared according to Examples 1 to 6 of the present invention are all good in wettability with the base material, coating film peeling, hydrophilicity, weather resistance, and corrosion resistance. On the other hand, the test piece of Comparative Examples 1-9 has a problem in any of wettability with a base material, coating film peeling, hydrophilicity, weather resistance, and corrosion resistance.
[0065]
【The invention's effect】
According to the photocatalyst coating composition of the present invention, it can be easily applied to the surface of a metal substrate such as an aluminum material, and a photocatalyst coating film having a long-term durability without a choking phenomenon can be easily formed.
In addition, the photocatalytic metal material of the present invention not only has excellent photocatalytic activity, but also has no choking phenomenon and long-term durability, so that it can be used for building materials, vehicle exterior materials, panel products, road incidental facilities, etc. It can be suitably used for many applications. Furthermore, according to the method for producing a photocatalytic metal material of the present invention, a photocatalytic metal material excellent in photocatalytic activity and durability can be produced at low cost without the need for special coating equipment or a baking furnace. it can.
Claims (9)
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| US6884752B2 (en) * | 2002-12-31 | 2005-04-26 | Prizmalite Industries, Inc. | Photocatalytically-active, self-cleaning aqueous coating compositions and methods |
| JP4844805B2 (en) * | 2005-05-20 | 2011-12-28 | 住友電気工業株式会社 | Method for forming metal coating |
| JP5164542B2 (en) | 2007-12-04 | 2013-03-21 | ニチハ株式会社 | How to paint building materials |
| JP2010107095A (en) * | 2008-10-29 | 2010-05-13 | Mitsubishi Electric Corp | Air conditioner |
| CN106696380B (en) * | 2016-12-12 | 2018-10-16 | 江阴通利光电科技有限公司 | A kind of light degradation formaldehyde film |
| JP2020127906A (en) * | 2017-06-09 | 2020-08-27 | 垰田 博史 | Base material, and method for producing the same |
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